Contact finger for electrical controllers and switches



Jane 22, I R. V. H. RUSSELL I CONTACT FINGER FQR ELECTRICAL CONTROLLERS AND SWITCHES Filed April 17, 1926 2 Sheets-Sheet 1 iillllllfl INVENTOR.

A TTORNEYS.

Jain. 22, 1929. A 1,699,858

R; V. H. RUSSELL.

CONTACT FINGER FOR ELECTRICAL CONTROLLERS AND SWITCHES Filed April 17', 1926 2 Sheets-Sheet 2 A TTORNEYS.

Patented Jan. 22, i 1929.

UNITED STATES PATENT OFFICE,

BOSLYN V. H. RUSSELL, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO ROSSELL MANUFACTURING 60., OF NIAGARA FALLS, NEW YORK, A CORPORATION OF NEW YORK.

GONTACT TINGER FOR ELECTRICAL CONTROLLERS AN 1) SWITCHES.

Application filed April 1'7, 1926. Serial No. 102,716.

This invention relates to a contact finger for electrical controllers or switches. Such fingers are raised and lowered continuously while working the controller drum with a which they are associated and in time these fingers, as heretofore constructed, became tired or take a set, thereby reducing the resilience 0f the same and ultimately causing thesame to break where the constant bending occurs, more especially where the finger has been weakened by punching holes therein for connecting the same with the tip and the base.

It is the object of this invention to provide a a contact finger which overcomes the above mentioned difficulty, and to that end this invention consists generally in supplementing the main metallic spring of the finger by an auxiliary spring which is preferably arranged along the outer side of the main spring and connected with the base and also exerts pressure on the tip, thereby re1nforc1ng the linger and permitting the same to rlse and fall without liability of breaking and yet engage properly with the drum.

In the accompanying drawings: Figure l is a side elevation of one form of contact finger embodying my invention.

Figure 2is a fragmentary longitudinal section of the same showing the means for connecting the central parts of the main spring and the auxiliary or reinforcing spring.

Figure 3 is a side view of the auxiliary H reinforcing spring.

Figure a is a plan view of the same.

Figure 5 is a side elevation of another form of contact finger containing my improvements.

Figure 6 is a side view of the auxiliary spring shown in Fig. 5.

Figure 7 is a top plan view thereof.

Figure 8 is a fragmentary side elevation showing a modificat on of the means for connecting the central parts of the main and auxiliary springs.

Figure 9 is a side elevation of another modification of my invention.

Figure 10 is a side elevation of the auxiliary spring shown in Fig. 9.

Figure 11 is a plan view thereof.

Similar characters of reference indicate corresponding parts in the several views of the drawings. a

The numeral 20 represents a main spring which is preferably of laminated form and constructed of a plurality of superposed strips of resilient sheet metal 21, 22. The lower or inner sheets 21 of metal of the main spring are comparatively thin and are provided adjacent to the rear end thereof with a transverse crimp or corrugation 23 for the purpose of holding the same against buckling crosswise. The outermost layer or sheet 22 of the laminated spring is made of comparatively thick resilient sheet metal and is provided. at its front end with a reversely or backwardly bent tongue 2a whereby this end of the main spring is converted into the form of a hook.

About midway of the length of the main spring its several layers are connected by a nal screw thread. i

On the front end of the main spring is an ranged a contact tip 26 which may be of any suitable form externally and which is preferably detachably connected with the main spring by providing the rear. side of the tip with a recess 27 which is engaged frictionally by the loop at the front end of the main spring as shown in Fig. 1. At its rear end the finger is secured to a bracket or base 28 formingpart of the controller stand, this connection being preferably effected by bolts or screws 29 passing through registering holes in the several layers in the rear end of the main spring and into said base or bracket.

'For the. purpose of strengthening the main spring and permitting the same to bendupon being raised and lowered while working the drum, reinforcing means are provided which, as shown in Figsl1-4 comprise an auxiliary leaf spring 31 of resilient sheet metal which is connected at its front and rear ends with the corresponding ends of the main spring while the central parts of the main and auxiliary springs are spaced apart but connected to each other forming in effect a truss-like 1 same bolts 29 which connect the main spring with said bracket. The front end of the auxiliary spring is provided with a plurality of transverse corrugations 32 which engage with the inner side of the hook shaped front end of the main spring and which, due to their rehollow rivet or ferrule 25 which has an inter- Ill silience, insure a good electrical contact between the auxiliary'spring and main spring and aid in holding the latter in good electrical engagement with the tip. The central parts of the main spring {1116 auxiliary spring are held in spaced relation, so as to form a truss effect, by a strut screw 33 passing through an opening in the central part of the auxiliary spring and engaging with the threaded bore ofthe ferrule 25, a collet or washer 34 surrounding the screw 33 and interposed between the main and auxiliary springs, and a clamping orjamb nut 35 arraugedon the strut screw and engaging with the outer side of the auxiliary spring.

By this means the collet forms a pier or anchor upon which the auxiliary spring rests and a trussed formation of the contact finger is Obtained which renders the same exceedingly strong and not liable to become set by constant use, yet retain the required resilience to ensure a yielding engagement of the same with the controller drum.

If it is desired to increase or decrease the plished by substituting either a thicker or thinner collet or washer for the one in use,

thereby either springing the arch formed by the auxiliary spring more or less, as required.

Instead of using collets or washers of different thickness foradjusting the resilience of the finger this same resultinay be obtained by providing the collet with e an internal screw thread which works on the thread of the strut screw and thus permits of arching the auxiliary spring as desired by running the collet and the clamping nut on the strut screw inwardly or outwardly as desired.

In Figs. 5, 6, 7 and 8, an organization of my invention is shown in which the front end of the auxiliary spring 37 is not provided with transverse corrugations nor does it engage with the loop of the main spring, but instead terminates short of this loop and bears against the body of the main spring immediately in rear ofthe loop.

If necessary the auxiliary spring instead of having its central part made plain as shown in Figs. 1, 3 and 4, the same may be provided with one or more longitudinal corrugations similar to those shown at 38 in Figs. 5, 6 and 7, for the purpose of stiffening this spring.

When a predetermined stiffness will answer the purpose in the contact finger the construction of the same can be materially simplified by permanently connecting the central parts of the main and auxiliary springs by a rivet 39, as shown in Fig. 8.

Another variation of my invention is emwith each other and to a support, said tip bodied in the structure shown in Figs. 9, 10 and 11 in which the tip 40 is formed on a rearwardly projecting shank 41 which is permanently connected with the front end of a main spring 36, an auxiliary spring 42 bears at its front and rear ends against said shank and main spring, respectively, and the central part. of the auxiliary spring and said shank are held in spaced relation to form an archedtruss bymeans of a screw 43 passing through the auxiliary spring and having threaded engagement with said shank, a collet 4L4 surrounding said screw and interposed between said shank and auxiliaryspring, and a clamping nut 45 arranged on said screw and bearing against the outer side of said auxiliary spring.

In all of the several forms of my invention herein shown and described the auxiliary form arranged over the main spring and engaging its front and rear ends withthe corresponding ends of the main spring, a strut connecting the elevated part of the arch of said 5 auxiliary spring with the adjacent part of a said main spring, and means connecting the rear ends of said main and auxiliary springs with each other and to a support.

2. A contact finger comprising a main spring, a tip mounted on the front end of the main spring, an auxiliary spring of arch form arranged over the mainspring and engaging its front and rear ends with the correspondingends of the main spring, a strut connecting the elevatedpart of thearch of said auxiliary spring with the adjacent part of said main spring, means connecting the rear ends of said main and auxiliary springs having a recess, the front end of the main spring having a reverse fold engaging said recess, and the front endof said auxiliary spring having corrugations which engage with the inner side of the folded front end of the main spring.

nosLYN v. H. RUSSELL. 

